I choose to cling to my delusions. About many things. 
LOL. @ChoatieMom - Can I cling to you? WTH.
I don’t know… I had two kids ( plus nieces and nephews ) at all BIG five BSs and when K2 ( arguably our most intelligent child ) toured them he kept mouthing " Moo" at me when no one else was looking . It got to the point where I couldn’t even look at him anymore because I’d burst out laughing.
Needless to say … K2 was looking for more of a boutique BS experience and found it… and this was a kid with three years of JBS under his belt and knew the SS/BS scene very well and could’ve survived anywhere.
To each his own.
All the BSs in the Top 30 ( regardless of size ) will give ANY student an amazing education/ experience. Pick the one that suits you best because the BS world is a surprisingly level playing field once you get there. . …
Suddenly “tiers” melt away … and BAM!
Trust me… it’s a shocker for some people. 
^^ That’s not the point. It’s tempting to defend anything and everything about our school, but it can get old. Outside the CC bubble, I suppose most people don’t talk about BS a lot, but if you do you should quickly figure out that the hierarch is very much there. As with any industry competing consumers, differentiation is one way to win but to learn from the forerunners in the industry and move closer to them is an easier and more common way especially the industry leaders cannot take all the consumers. Then again, one would ask what does that have to do with me? My kid is at school D and I say school D is the best if not in the whole world at least for my kid. Fair enough. Just don’t make it sound like there’s no difference among schools. Sorry if I offended anyone, in advance.
@sadieshadow, optimal size is like beauty–in the eye of the beholder. Some students like small schools, others like larger schools. Of course, even a “large” boarding school pales in comparison to many public high schools.
It is thought that students at larger boarding schools can be more specialized, more “lopsided” if you will, because the larger size gives admissions teams more opportunities to create a class.
Choate and Deerfield are fine schools. I have no idea which is “better” than the other. I think only each school’s board of trustees knows what the schools plan to do in the immediate future.
@gnarwhail You seem to know quite detailed information on several schools. Are you willing to tell us how you know all that you do? It might help some of us to put your comments into context. I understand if you don’t want to say, but I, for one, would be interested.
@GnarWhail, Maybe I’m missing something here, but why would you think allowing long-commute day students is all about attracting full-pay families? For one thing it’s counterintuitive. A boarding student on FA costs the school more than a day student on FA.
I’m also curious about where your information comes from. Do you sit on the board at one of these schools? I’ve been a board member at a similar school and my experience matches more closely with ChoatieMom’s than yours.
BTW, have we defined long commutes? What is a long commute? A half hour? An hour?
I don’t want to shock anyone, but for as much as our son’s experience at Choate was positive and prepared him well for college, Choate was not MY first choice, and I am not here to defend Choate or to try to tell anyone that Choate is better than any other BS. How in the world would I even know that? It’s the only BS I have experience with, and I often couch my comments with the phrase, “I can only speak to Choate…” Choate may be a mediocre BS for all I know, but I would have no way judging that because I only know the one school. I always and only speak from my personal experience, and I think I’m pretty clear about that. I have learned from my time on this forum, that we did not cast a wide net, and I will forever regret that we were unaware of good boarding schools much closer to home – and that I did not know @ThacherParent in advance.
Anyway, I’m no authority on boarding schools. I just like to chime in when I feel something relevant about our experience can add to the conversation. I certainly don’t have @GnarWhail’s experience.
Maybe gnarwhail doesn’t have the experience he/she thinks, either. Sometimes, we don’t know what we don’t know regardless of opinions.
@choatiemom I think what we have observed here is not that posters outright say their school is THE best but rather they tend to rave about their schools with lots of compliments and have a hard time acknowledging any shortcoming or being patient with any questioning (the questioners’ motivations would be questioned and quickly asked to stay away etc.). So the effect is that one has to think that school is PERFECT (minus a disclaimer: BS is not for everyone). It’s great everyone has positive experience with their schools, but let’s not kid ourselves - no school (nowhere really) is utopia. There are good and bad, happy and mad incidents/moments every day. The school administrators, teachers, dorm parents and peers trying hard as they may be make mistakes all the time. I think to keep things in perspective and TRY to be somewhat objective is more helpful to those who are here to look for information and help than throwing cheering parties every day and taking it as a cause to fend off anyone who dares to question.
As someone who attended one of those other boarding schools, Choate is far from mediocre. 
@Sue22 Not sure I understand your statement regarding day students. A school that needs or wants more money can accept a greater number of full-pay day students without making major investments in the campus. No school ever boasts about having more day students, but they often boast about increasing their boarding percentage. I’m not saying that is a good thing or a bad thing, right or wrong, but it is the way of this tiny world.
A long commute is one longer than it takes to walk to from the average dorm room to the center of campus–hassle, time outa your day wasted in the car, and so on. Too long? Well, that’s a point of contention apparently, but check out schools that have no day students or limit the commute with admissions standards.
@london203 You are correct that I am not going to give out any info which might identify me. Nope. I will say that I have been in and around this weird little boarding/prep school world for long enough to understand what it is really all about beyond both the twaddle and the pompous inanity as well as the petty gossip. And I have great love for what the schools can be to the right students and am a great booster of the possibilities to be found there. I always advise people to ignore the best and worst things they hear about any school they are considering, whether they are prospective students, parents, or anyone else.
@Periwinkle The thing is that what any of the schools are planning at any given time is almost exactly what all the other schools are planning. Not down to the millimeter surely, but in general? Oh yeah. And I’m talking about the most elite, selective schools–the lower on the food chain a school is, the more likely it is to do whatever is necessary to keep the lights on. Consider it from the other direction: who applies to these schools and where do they come from and how many of them are there? Then more specifically: who is accepted by these schools and where do they come from and how many of them are there? Even more specifically: who pays full boat for these schools and where do they come from and how many of them are there? Very few, all things considered, so no school is going to do a single thing which might alienate any one of these potential students. Any given school might blather about being a unique institution for the very specialest of special snowflakes, but in reality these schools know their audience and stick very closely to what is conventional wisdom for that particular cohort.
@gnarwhail Fair enough. But it does make it hard to accept your comments at face value without some level of context or basis for the various opinions you express. Oh whail.
I actually think you need to take into account the best and the worst you hear about any given school - that gives the truer picture of the range of possibility. But we will agree to disagree.
@GnarWhail - you sound like a disaffected BS parent who found themselves on the losing end of an argument about your own school’s day/boarder ratio. So many pronouncements! Long day-student commutes are stupid and a sign of weakness, check. You know elite when you see it, check. You know that the market has spoken about “best size,” check. You know that most people on this site just can’t see the forest for the trees, check.
@GnarWhail, now I get your point. I wasn’t thinking about schools expanding their populations. I don’t have any stats to back this up but my impression from friends who attended these schools as day students in the 70’s and 80’s is that the day/boarder mix has not changed substantially, although a few schools have increased their sizes a bit. In some cases the limiting factor is spaces used by both day and boarding students, like the school chapel, the auditorium, or the dining hall. It’s not all that hard to build a new dorm.
I’ve never heard a boarding school boast about decreasing their day population. I have heard schools talk about why they feel their day/boarding mix is right for them.
In my area boarding schools use the day option to compete with the rich plethora of day school options available to local families. Many of these families would not send their kids to boarding school at 14 or the kids themselves do not feel ready to board. A deciding factor for some families is the ability to switch from day to boarding or back, something not allowed by some of the schools. Most families around here seem to see 30 minutes without traffic (sometime longer with it) as a soft limit. Some schools offer buses from target communities.
We’ve had a kid at a strictly day school, a boarder, and a day student at a boarding school. All have their plusses and minuses. My kid who boarded is urging my day-at-boarding kid to remain a day student, as she feels it’s the best of both worlds. Day-at-boarding kid would spend every hour available at school and wants to board. Day-at-day was very happy commuting from home. To each his own.
It’s interesting that you say that
because in my area many, even most of the highly competitive boarding schools are in the 300-350 range. Among these are Concord Academy, Middlesex, Brooks, CSW, St. Mark’s and St. George’s. Milton has a K-12 population of 700, but only about 300 students live on campus. Groton’s 8-12 population comes in at around 370. Outside the Greater Boston area Cate, Emma Willard, St. Andrew’s, Thacher and many other fine boarding schools are in this range.
As to the original question, larger schools often offer a wider array of sports, but the flip side of this is that smaller schools often make it easier for kids to participate in multiple extracurricular activities at the same time, as they need to fill all those slots with a smaller student population. IOW, if your kid is a competitive swimmer a large school might be better. If they want to be in the winter play and still play basketball a small school might be best. YMMV. As a few posters above noted, it’s sometimes easier to take on a leadership role at a smaller school.
In the end the OP’s question is a lot like asking, “Should I attend a big university or a small LAC?” It depends on the student, their interests, the size of the school they’re coming from, and their basic personality. Some kids find a large school impersonal, others find it energizing; some kids find a small school stifling, others find it nurturing. Most kids have a pretty good sense of what’s right for them.
@GnarWhail, Unless you’re somehow in a privileged position to see inside the planning practices of multiple schools I don’t see how you can claim this. I see schools following similar paths in some ways, for instance becoming more tech savvy and global, but diverging in others. Some schools are forging ahead with more and more AP’s, some are doing away with them altogether. Some schools are sticking to primarily traditional teaching methods, others are going to a flipped classroom model. Schools with specific strengths, like outdoor education, religious education or the Harkness table will continue down those paths while other schools stick to their traditional methods.
@posters are taking @GnarWhail too seriously. Sorry @GnarWhail, you are a different voice and “fresh air”, but i don’t take your words too seriously. What “market” says ~600 is ideal size. “The market” says 1000+ is better because those two schools are successful in every possible way a prep school can be. Schools with ~600 students are a mixed bag with some among the industry leaders and others lagging behind. Small schools are more for the needs of a “niche market” so many of them have been and will stay the way they are.
Isn’t Loomis Chaffee publicly attempting to increase their boarding population?